Printing press



July 4, 1939. G. c. WATERS PRINTING PRES S Filed Dec. 24, 19 56 3Sheets-Sheet l INVENTOR Gilbert L. I Vizters ATTORNEYS July 4, 1939. cWATERS 2,164,363

PRINTING PRESS Filed Dec. 24, 1936 3 Sheets-Sheet 2 CONTROL INVENTORGilbert C- Waters y 4, 1939- I G. c WATERS 2,164,363

PRINTING PRESS Filed Dec. 24, 1956 3 Sheets-Sheet 3 l )l| I 54 I 57 I yI i 64- 5 o o 8 Z F1 .11 38 J INVENTOR BY Gilbert 0'- Waters ATTORNEYSPatented July 4, 1939 UNITED STATES PATENT OFFICE 15 Claims.

This invention relates to an improvement in printing presses. In itsbroader aspect it is adapted to all types of printing, letter press,gravure, and lithographic, and in each gives dis- 5 tinct advantage. Itis peculiarly adapted to letter press printing from rubber, or otherresilient type faces.

Printing from a resilient type face is now well known. It offers theonly practical solution for 10 printing certain types of work, but theusefulness of the process has been realized to a limited extent onlybecause of the limitations of existing presses.

Perfect letter press printing can only be achieved if the type facemeets the sheet and delivers its imprint along the true pitch line orplane in which the linear speed of the sheet is exactly equal to theperipheral speed of the printing surface. This holds true for both fiatbed and rotary printing. But a true pitch line is never achieved. Slightbut cumulative inaccuracies in the machining of the press; in the heightof the type or plate, and in the application of forms or plates to thepress always occur,

unison with the sheet being printed upon.

Thus the printer is driven to the make-ready operation which consists inbuilding up under the type face or under the draw-sheet a laminatedstructure of bits of paper or fibre. He is forced to do this because ofthe inaccuracies which have crept into the press, the plate or thepaper. But the make ready operation only approximates the desiredresult. The variations from true cylindrical form and the variationsfrom the correct diameters bring the sheet surface out of the pitchplane common tothe two cylinders with the result that there is slipbetween the sheet and printing cylinder.

In printing from metal, fairly satisfactory results are obtained for thereason that the metal pounds into the packing and establishes animpression bed, which although not in the true pitch plane and henceinaccurate, still gives fairly good results.

When, however, a flexible printing surface is used, the type, because itis resilient, is forced back and no static condition, as in the case ofmetal plates, ever is established. Instead, the packing is forced intothe plate and the working pitch line is established somewhere below theactual working surface of the plate. Different kinds of surfaces onpaper and other materials being printed upon require different pressuresand different kinds of ink also require different pressures. Eachdifferent pressure establishes a plane of contact between the resilientcylindrical plate surface and the sheets being printed upon at differentdistances from the axis of the cylinder. While the variations in thespeed of and the printing surface never moves exactly in the cylinderand sheet may not be great enough to be apparent upon inspection of theprinted sheet the slip between the rubber plate and sheet material beingprinted greatly shortens the life of the rubber plate.

It is believed that the inability to eliminate slip accounts for thegreat variation in the life of rubber printing plates run under whatseem to be identical conditions, i. e., ink, paper, press speed andcharacter of printed image. times the pressman has his press packed atexactly the correct cylinder diameter. More often he has not, since thelong lived rubber plate is the exception and short runs are the rule.

An important object of the present invention is to provide a device bywhich variations in the effective diameter of the printing cylinder maybe quickly and easily compensated for by effecting extremely minutevariations in the ratio between the peripheral speed of the cylinder andthe linear speed of the sheet material engaged by the cylinder.

Further objects of the invention are to provide a press of lightconstruction capable of producing, accurate work at high speeds and toprovide a press having a wide range of useful- .ness and readyadaptability to the printing of continuouswebs or individual sheets.

With the above and other objects in view the invention may be said tocomprise the device as illustrated in the accompanying drawings,hereinafter described and particularly set forth in the appended claimstogether with such variations and adaptations thereof as will be readilyapparent to those skilled in the art.

Reference should be had to the accompanying drawings forming a part ofthis specification, in which:

Figure 1 is a side elevation of a printing press embodying theinvention; v

Fig. 2 is a diagrammatic view illustrating the operation of the speedchanging device associated with the sheet feeding belt which serves asthe impression member;

Fig. 3 is a vertical section taken on the line indicated at 33 in Fig.1;

Fig. 4 is a sectional detail view of the pulley adjusting device;

Fig. 5 is a top plan view of the machine;

Fig. 6 is a diagrammatic view showing the driving connections in sideelevation;

Fig. 7 is a side elevation showing a device for regulating the feed ofsheets to the printing cylinders;

Fig. 8 is a top plan view of the feed regulating device;

Fig. 9 is an enlarged side elevation showing the stop devices and meansfor actuating the same;

Fig. 10 is a section taken on the line indicated at llllt in Fig. 9;

Some- Fig. 11 is a diagrammatic view showing the invention applied to amulti-cylinder press.

In the accompanying drawings the invention is shown applied to aprinting press in which the printing member is in the form of a cylinderI and the impression member is in the form of an endless belt 2. Thebelt 2 runs over pulleys 3 and 4 mounted on shafts 5 and 5 at the endsof a rigid supporting frame 1 which supports both the cylinder and thebelt and which is rigidly secured to a side plate 8 of a supportingframe 9. The frame I is attached at one side to the supporting frame 9and is open at the other to facilitate the removal of the belt, cylinderand other parts of the press. The upper run of the belt which carriesthe sheet material to the printing cylinder is supported by a bed Inwhich is mounted for vertical adjustment on the frame I, suitableadjusting means such as screws II being provided for raising, loweringand leveling the bed.

The printing cylinder I is fixed to a shaft I2 which is journalled inbearing blocks I3 which are mounted for vertical adjustment on suitableguide posts I 4 secured to the frame I and projecting upwardlytherefrom. The bearing blocks I3 are resiliently supported by means ofcoil springs I5 interposed between the frame I and the bearing blocksand surrounding adjustable stop screws I6 which limit the movement ofthe cylinder toward the belt and determines the operative position ofthe cylinder. The bearing blocks I3 are held in engagement with thepositioning screws I6 by means of vertical pins II which are interposedbetween the tops of bearing blocks and cams I8 carried by a cross shaftI9 above the cylinder to which is attached suitable handle 20. By meansof the cams I8 the pins [1 are forced downwardly to press the bearingblocks against positioning screws IE to hold the .cylinder I in ,a fixedposition. When the cams I8 are moved to a releasing position by means ofa handle 20 the cylinder I is lifted by the springs I5 out of printingposition.

A suitable printing plate such as rubber printing. plate 2| is. attachedby suitable means to the periphery of the cylinder. Ink is supplied tothis plate by a conventional inking mechanism 22 which is slidablymounted on ways 23 so that it can be backed away from the cylinder whendesired. .I

A suitable driving connection is provided between the impression belt 2and the printing cylinder I,this driving connection being such that theperipheral surface of the printing plate and the ,top surface of thebelt travel at exactly the same speed, assuming the belt and printingplate to be both uniform and of the correct predetermined thicknesses.Any suitable positive drive gearing may be employed which will maintaina constant speed ratio between the shafts 5 and I2. As herein shown, thedrive is a chain and sprocket drive, the cylinder shaft I2 beingprovided with a sprocket 24, the shaft 5 and 5 of the belt pulleys beingprovided with sprockets 25 and 26. A sprocket chain 2'! runs over thesprockets 25 and 26 and engages the under side of the sprocket 24,suitable means such as an idler 28 being provided for maintaining apositive driving engagement between the chain 21 and sprocket 24.

The positive driving connection between the belt pulley 3 and thecylinder I provides the correct speed ratio provided the printing plateis of exactly the correct thickness, and assuming that there is nodistortion of the printing plate at the point of contact with the sheetmaterial being printed upon. However, in actual practice thetheoretically correct condition is not obtainable. The rubber printingplate may be two or three thousandths of an inch thinner or thicker thanthe thickness specified, and, as pointed out above, these plates, due totheir resiliency, are flattened more or less by the pressure appliedthereto during the printing opera tion. The variations in platethickness and the variations in pressures applied to the plates duringprinting vary the distance of the printing surface from the axis of thecylinder with the result that the actual speed of travel of the cylinderat the point of contact with the work will vary slightly from the speedof the belt and this variation results in slip between the printingplate surface and the sheet material being printed upon. If the point ofcontact is, say, .001" above or below the true pitch line of thecylinder the amount of slip per revolution of the cylinder will be 21r.001". In the terms of speed ratio the variation is extremely minute. Interms of the amount of slip in a days run the slippage becomesconsiderable and its effect upon the rubber printing plates is verydeleterious.

The present invention provides a means for positively and accuratelychanging the speed ratio between the printing member and the impressionmember within the extremely minute range of variations in the effectivediameter of the printing cylinder due to variations in thickness of theprinting plate and variations in the pressure applied to the printingplate.

In the machine herein shown, changes in the speed ratio between theimpression belt and printing cylinder are effected by changing theeffective diameter of the belt pulley which is geared to the cylinderand the variations in pulley diameter are effected by changing the tensionof the impression belt 2. In order to enable varying tensions to beapplied to the belt the shaft 5 is mounted in sliding bearing blocks 29which are mounted in slots 30 in the forward end of the frame I, thesebearing blocks being adjustable in the slots by means of longitudinalscrews 3I threaded in the fixed portions of the frame and exertingthrust against the rear faces of the bearing blocks 29. Each of the twoscrews 3| has a sprocket 32 fixed thereto and a sprocket chain 33 runsover these sprockets which causes the screws to turn in unison to shiftboth bearings of the pulley shaft 5 simultaneously. For aligning thepulley with the belt, an additional screw 34 may be provided whichextends through one of the screws3l, which is made hollow, and engageswith the rear faces of one of the bearing blocks 29. By adjusting thescrew 34 the pulley 3 may be adjusted to establish uniform pressureagainst the interior of the belt throughout the width of the belt.

The pulley 3 is covered with a layer 35 of rubber of uniform thicknesswhich extends throughout the periphery of the pulley. The rubbercovering 35 is composed of elastic rubber so that the thickness thereofin the portion of the pulley engaged by the belt will vary with theradial pressure exerted by the belt upon the pulley. As the pressure ofthe belt against the face of the pulley is increased the effectivediameter of the pulley is slightly decreased. If the pressure of thebelt on the pulley is lessened the effective diameter of the pulley isslightly increased. If the pulley is driven by the belt, a decrease inthe effective diameter of the pulley will increase the speed of rotationof the shaft and of the cylinder I geared to the shaft 5. If the shaft 5is driven, a decrease in the diameter of the pulley will decrease thespeed of travel of the belt. The effect on the speed ratio between theimpression belt and printing cylinder isthe same in both cases. Thevariation in the effective diameter of the pulley 3 necessary to effectthe corrections in the speed ratio to correspond substantially to thevariations of the actual contact planes from the true pitch line of thecylinder established by the gearing connecting the pulley shaft 5 andthe cylinder shaft I2, and, since these Variations are measured in avery few thousandths of an inch, the variation in pulley diameter alsoneed be only a very few thousandths of an inch. Within the narrow limitsrequired for the corrections desired, the pulley diameter can beaccurately Varied by varying the tension of the belt. By providing alayer 35 of rubber of the proper thickness and of the proper degree ofelasticity, very accurate control of belt speed may be obtained. Theeffect of variations in belt tension on the belt to cylinder speed ratiomay be accurately determined by accurately measuring the differences inthe travel of the belt for a given number of revolutions of the beltpulley 5 with various tensions applied to the belt. For example, apredetermined tension may be applied to the belt and a mark on the beltmay be alined with a mark on the bed. A given number of revolutions maythen be imparted to the pulley and a second mark be made on the bedopposite the mark on the belt. The tension of the belt may then beincreased or decreased a predetermined amount, the belt adjusted toitsoriginal starting position and the same number of revolutions beimparted to the pulley. The distance of the mark on the belt from thefirst stopping point divided by the number of revolutions times 2 willbe the change in effective pulley radius. The speed ratio changeseffected by various tensions within the desired range may thus beaccurately determined. The distance of the cylinder axis from thesurface being printed upon may be accurately gauged for a series ofpressures within the desired range and the proper adjustments of thepulley 5 may be made to compensate for variations in plate thickness andfor variations in the pressure applied to the plates during the printingoperation.

Where, as shown herein, the two belt pulleys are geared together, thepulley 4 is also preferably provided with an elastic covering 35 so thatthe effective diameters of both pulleys are simultaneously changed. Thechanges in speed ratio are, however, effected by the pulley geared tothe cylinder and it is not essential that both pulleys be provided withan elastic covering.

In Figs. 1 and 5, of the drawings, the invention is shown applied to theprinting of continuous webs of paper or similar material. The paper istaken from a roll 36 mounted in suitable bearings provided in the rearend of the frame 9, passes from the roll 36 over a fixed pulley 3? downunder a movable take-up pulley 38 and upwardly over the pulley 4 ontothe upper run of the belt 2. The pulley 38 compensates for variations inthe rate of feed of paper from the roll and provides a yielding tensionregulating device which prevents excessive tension on the web instarting the machine into opera tion. The pulley 38 travels in avertical slot 39 provided in the frame which is of a length sufiicientto allow the necessary play of the roller. In order to preventoverrunning of the unwinding roll 36 during the unwinding operation, asuitable braking device is applied to the roll 36. For convenience ofillustration, an ordinary paddle brake 4E1 engaging the surface of theroll 35 is shown. At the forward end of the machine the paper is woundup on a reel 4| which is carried on a shaft 42 detachably mounted insuitable bearings 43 on the frame. One end of the shaft 42 is detachablykeyed to a clutch member 44 which is rotatably mounted on the shaft 45of an electric motor 46. A shiftable clutch member 41 is splined to themotor shaft 45 and is engageable with the clutch member 44 to cause theclutch member to rotate with the shaft and drive the wind-up reel. Thesplined clutch member 41 is moved by a suitable shift lever 48 be tweenthe clutch member 44 and the second clutch member 49 rotatably mountedon the shaft 45. The clutch member 49 carries a sprocket 5E! and drivesthe shaft 5 through a sprocket 5| on the shaft 5 and a sprocket chain 52which runs from the sprocket 56) to an idler 53 and bears against theunder side of the sprocket 5i on the shaft 5. The motor 46 can be usedto drive either the wind-up reel 4! or the belt pulley 3 as desired. Inprinting on continuous webs it is ordinarily preferable to drive thebelt from the web. In order to maintain sufhcient friction between thebelt and the web the paper passes in a substantially vertical directionup to the pulley 4 and down from the pulley 3, so

that the paper under tension has an effective frictional grip on thebelt over a considerable arc of each of the pulleys. To provideadditional friction between the paper and the belt surface, one or morepressure rollers 54 are provided which press the paper against thesurface of the'belt. The shaft of the roller 54 is engaged by pivotedspring arms '55 and the pressure of the roller against the paper may beadjusted by means of screws 56. Additional pressure may be exerted uponthe paper by means of a series of metal rods 51 pivoted to cross bar 58above the belt and lying upon the top surface of the paper passing overthe belt.

In order to maintain a constant speed of travel of the paper web, asuitable motor control is provided for varying the speed of the motor tocompensate for variations in the diameter of the roll of paper on thereel 3! as is common practice in the art. The control device includesroller 59 which presses against the roll of paper on the reel 4|, theroller 59 being carried by a? controller arm 60 fixed to a shaft t lwhich. extends into a control box 62 which contains conventional currentcontrolling devices for varying the speed of the motor proportionally tothe movements of the controller arm.

When printing upon webs of material which is elastic or which does nothave sufficient tensile strength to drive the printing mechanism, thebelt 2 may be driven direct through the sprocket chain 52, and, whenindividualsheets are being printed the direct drive from the motor tothe belt is utilized.

In Figs. 7 to of thedrawings, the press is shown adapted for theprinting of individual sheets. The sheets are delivered one at a time tothe impression belt 2 by a suitable chute 63 and are carried one at atime by the belt to the printing cylinder. In order to properly registerthe sheets with the printing plate on the cylinder a suitable stopdevice is provided in connection with the belt 2 for stopping individualsheets and releasing them at intervals properly timed with respect tothe rotation of the printing cylinder. The stop devices are carried by arocker frame 64 which extends across the upper run of the belt and hasdownturned end portions 65 connected to the frame by horizontal pivots86. Forwardly and rearwardly extending arms 6! and 68 are attached tothe rocker frame 5 5. These arms have end portions 69 bent downwardly atright angles and have V-notches which provide spaced belt engagingfingers 1B. The arms El and 6B are relatively rigid and the fingers 19have rolled lower edges H which are adapted to rest upon the belt. Thearms 6'! and 68, each carry a spring metal stop member 12 which has anend portion 13 bent down at right angles and forming a stop finger. Thestop fingers 13 are in front of and closely adjacent the downturned endportions 69 of the arms 6'! and 83 so as to be held against deflectionin the direction of the travel of the belt.

The stop fingers 13 are adapted to be adjusted by means of screws 14 tovary the distance which these stop fingers project below the rollededges of the fingers to thereby vary the pressure with which these stopfingers are pressed against the surface of the belt. The rocker frame 84carries a pressure roller 15 which is brought into engagement with thepaper when the frame is rocked rearwardly to bring the rear stop fingersinto engagement with the belt. The rocker frame G l is actuated atintervals timed with respect to the rotation of the cylinder I, beingprovided with a rearwardly extending arm 16 which is engaged by a spring11 which acts to normally hold the frame in a position in which theforward stop fingers engage the belt. The rocker frame 64 is alsoprovided with a rearward extending arm 18 which carries an adjustableset screw 79 engaged by an actuating lever 80 which is pivotedintermediate its ends at 8! to the frame and which engages a cam 82fixed to one end of the printing cylinder. The major portion of the cam82 is circular and concentric with the cylinder, but, at a pointcorresponding to the position of the space between the ends of theprinting plate on the cylinder, the cam has a recessed portion 83.Throughout a major portion of the rotation of the cylinder the cam 32holds the rocker arm in the position in which the rear stop fingers arein engagement with the belt. Whenever the lever 80 comes into engagementwith the recessed portion 83 of the cam the rocker frame is released andismoved by the spring H to a position in which the forward stop fingersengage the belt.

In operation a sheet of paper on the belt first engages the rear stopfingers 13 and is held against further movement with the belt until therecessed portion 83 of the cam engages the lever 8%], whereupon therocker frame is released and the rear stop fingers are lifted. The papersheet held by the rear stop fingers is then released and moves forwardinto engagement with the forward stop fingers and is held by the forwardstop fingers until the lever 80 rides out of the depression 83 of thecam, whereupon the sheet is released by the forward stop fingers andpasses with the belt beneath the printing cylinder, the release of theforward stop fingers being so timed with respect to the movement of thecylinder that the sheet is properly registered with the printing plate.When the rocker frame is returned to the position in which the rear stopfingers are in operative position, these fingers may rest upon the topof the sheet previously stopped by forward stop fingers, but thisengagement does not hinder the passage of this sheet to the cylinder.However, any additional sheet will be stopped even though it partiallyoverlies the sheet being fed to the cylinder. The cam 82 is attached toone end of the cylinder by means of bolts 84 which pass through arcuateslots 85 in the cam so that the cam can be adjusted to proper angularposition on the end of the cylinder.

The press herein shown may be a unitof amulticylinder press as shown inFig. 11 of the drawings. By simply arranging the units end to end sothat the paper is fed from one belt to the next the printing ofsuccessive cylinders may be registered. The belts may be continuouslydriven by means of a web of paper fed from a feed roll 3'5 to a wind-upreel 4| operating in exactly the same way as in Fig. 1 of the drawings.Each cylinder is provided with an individual impression belt so that thenecessary changes in speed ratio may be made between each of the beltsand its associated cylinder. Since the belts are all driven from onemoving web the speed of the belts will be the same, but by changing theeffective diameters of the pulleys 3 the speeds of rotation of theprinting cylinders may be adjusted as desired to reduce slippage betweenthe individual cylinders and the moving web of paper.

It will be apparent that the present invention provides a printing pressof very light construction capable of operating at high speed, whichrequires but little power for its operation and which, by reason of itscapability of minute speed adjustment is capable of very exact anduniform printing with very little wear on parts such as the printingplates.

Furthermore, it is to be understood that the particular form ofapparatus shown and described, and the particular procedure set forth, I

are presented for purposes of explanation and illustration and thatvarious modifications of said apparatus and procedure can be madewithout departing from my invention as defined in the appended claims.

What I claim is:

l. A printing press comprising an impression member and a printingmember between which sheet material may be fed, means for driving saidmembers in directions such that the surfaces thereof engaging the sheetmaterial travel in the same direction and at speeds such that theopposed faces of said members in engagement with the sheet materialtravel at approximately the same speed, said driving means including acylindrical driving pulley through which motion is transmitted toone ofsaid members, and means for effecting minute increases or decreases inthe effective diameter of said pulley to effect minute changes in thespeed of the member driven by the pulley to equalize the speeds of thematerialengaging surfaces of said members.

2. A printing press comprising a bed, an endless belt passing over saidbed, a printing cylinder engageable with sheet material being carriedover the bed by the belt, pulleys over which the belt passes, one ofsaid pulleys being adjustable to Vary the tension of the belt, andgearing connecting said cylinder with the adjustable pulley.

3. A printing press comprising a bed, an endless belt passing over saidbed, a printing cylinder engageable with sheet material being carriedover the bed by the belt, a pulley over which said belt passes, gearingconnecting said cylinder with said pulley, means for delivering a stripof sheet material to the belt, means independent of the cylinder forpressing the strip against the belt, and means for pulling the stripthrough the press whereby the belt and cylinder are driven by saidstrip.

4. A printing press comprising a bed, an endless belt passing over saidbed, a printing cylinder engageable with sheet material being carriedover the bed by the belt, a pulley over which said belt passes, gearingconnecting said cylinder with said pulley, means for delivering a stripof sheet material to the belt, means independent of the cylinder forpressing the strip against the belt, means for pulling the strip throughthe press whereby the belt and cylinder are driven by said strip, adriving mechanism, and means for connecting said driving mechanism tosaid belt pulley or to said strip-pulling means.

5. A printing press comprising a bed, an endless belt passing over thebed, a printing cylinder engageable with sheet material being carriedover the bed by the belt, means for driving the belt and cylinder, andmeans for effecting minute changes in the speed ratio to equalize thespeeds of the material engaging surfaces of said members.

6. A printing press comprising a bed, an endless belt passing over thebed, a printing cylinder having a resilient printing plate engageablewith sheet material being carried over the bed by the belt, means foreffecting relative adjustments of the bed and cylinder to vary thepressure applied to the sheet material, means for driving the belt andcylinder, and means for effecting minute changes in the speed ratio toequalize the speeds of the material engaging surfaces of said members.

7. A printing press comprising a bed, an endless belt passing over saidbed, a printing cylinder engageable with sheet material being carriedover the bed by the belt, a pulley over which said belt passes, gearingconnecting said cylinder with said pulley, and means independent of saidgearing for varying the ratio between the linear speed of the belt andthe peripheral speed of the cylinder.

8. A printing press comprising a bed, an endless belt passing over saidbed, a printing cylinder engageable with sheet material being carriedover the bed by the belt, a pulley over which said belt passes, gearingconnecting said cylinder with said pulley, and means for varying theeffective diameter of said pulley to vary the ratio between the linearspeed of the belt and the peripheral speed of the cylinder.

9. A printing press comprising a bed, an endless belt passing over saidbed, a printing cylinder engageable with sheet material being carriedover the bed by the belt, a pulley over which said belt passes, saidpulley having a layer of elastic compressible material upon itsbeltengaging periphery, means for varying the tension of the belt tovary the pressure exerted by the belt on said elastic layer and changethe efiective diameter of, said pulley, and gearing connecting saidpulley and said cylinder.

10. A printing press comprising a bed, an endless belt passing over saidbed, a printing cylinder engageable with sheet material being carriedover the bed by the belt, a pulley over which said belt passes, saidpulley having a layer of elastic rubber extending around its peripheralbelt-engaging periphery, means for adjusting said pulley to vary thetension of the belt, thereby varying the pressure exerted by the belt onthe elastic rubber covering of the pulley and varying the effectivediameter of said pulley, and gearing connecting said pulley and saidcylinder.

11. A printing press comprising a bed, an endless belt passing over saidbed, a printing cylinder engageable with sheet material being carriedover the bed by the belt, pulleys over which the belt passes, one ofsaid pulleys having a layer of elastic rubber extending around itsbelt-engaging periphery, one of said pulleys being adjustable to varythe tension of the belt, and gearing connecting the rubber shod pulleywith the printing cylinder.

12. A printing press comprising a bed, an end less belt passing oversaid bed, a printing cylinder engageable with sheet material beingcarried over the bed by the belt, a pulley over which said belt passes,gearing connecting said cylinder with said pulley, means for varying thetension of said belt, and means responsive to changes in belt tensionfor changing the ratio between the linear speed of the belt and theperipheral speed of the cylinder.

13. A printing press comprising a bed, an endless belt passing over saidbed, a printing cylinder engageable with sheet material being carriedover the bed by the belt, said cylinder having a resilient printingplate thereon, means for relatively adjusting the cylinder and bed forvarying the pressure exerted on the sheet material between the bed andthe cylinder, a driving connection between the belt and cylinder, andmeans for varying the speed ratio between the cylinder and belt tocompensate for variations in the thickness of the printing plate andvariations in the pressure to which the plate is subjected in printing.

14. A printing press comprising an impression member and a printingmember between which sheet material may be fed, means for driving saidmembers in directions such that the surfaces thereof engaging the sheetmaterial travel in the same direction and at speeds such that theopposed faces of said members in engagement with the sheet materialtravel at approximately the same speed, and driving means including apulley and belt, the surface of said pulley in engagement with said beltbeing substantially cylindrical, through which motion is transmitted toone of said members, and means for effecting minute increases ordecreases in the efiective diameter of said pulley to effect minutechanges in the speed of the member driven by the pulley to equalize thespeeds of the material-engaging surfaces of said members.

15. A printing press comprising a bed, an endless belt passing over saidbed, a printing cylinder engageable with sheet material being carriedover the bed by said belt, a pulley over which said belt passes, gearingconnecting said cylinder with said pulley, means for delivering a stripof sheet material to the belt, means for tensioning said strip and forcausing the strip to press against the belt, and means for pulling thestrip through the press, whereby the belt and cylinder are driven bysaid str p- GILBERT C. WATERS.

